A silicon carbide is expected as a material for next generation semiconductor devices. In comparison with silicon, the silicon carbide has superior physical properties such as a band gap of about 3 times, a breakdown field strength of about 10 times, and a thermal conductivity of about 3 times. By utilizing these characteristics, for example, it is possible to realize a metal oxide semiconductor field effect transistor (MOSFET) which can operate at a high breakdown voltage, a low loss, and a high temperature.
A vertical type MOSFET using silicon carbide has a pn junction diode as a parasitic built-in diode. For example, the MOSFET is used as a switching element connected to an inductive load. In this case, even when the MOSFET is turned off, by using a pn junction diode, it is possible to allow a reflux current to flow.
However, when a reflux current is allowed to flow by using a pn junction diode, stacking faults grow in the silicon carbide layer due to the recombination energy of carriers, and thus, there is a concern that the on-resistance of the MOSFET may increase. An increase in the on-resistance of the MOSFET causes degradation in the reliability of the MOSFET.